Well differences between upped/unupped are closely related to why people choose to not up certain cards.
I choose to not up FFQ because it is different from elite FFQ in that its fireflies make light, which powers my hope shield.
I choose to not up Mind Flayer because it's different from ulitharid (cheaper, but lower defense), so I can start lobo-ing things faster
Emphatic bond / steal make no sense, though, since there's no reason I can think of to not upgrade them, other than a lack of money